Throttle return spring redundancy system

ABSTRACT

A throttle valve, situated within the induction passage bore of a fuel or air induction device, is carried by a throttle shaft for fixed rotation therewith; a lever arrangement fixedly connected to the throttle shaft is operatively connected to a remotely situated operator&#39;&#39;s foot-operated throttle control; a first throttle return spring is operatively connected to the first lever for returning the throttle valve to an idle position whenever the foot-operated throttle control is released; and a second safety spring is provided for, in one embodiment of the invention, assuring the movement of the throttle valve to the idle position and, in another embodiment of the invention, deactuating the engine ignition system, in the event that, for example, either the first throttle return spring or the associated throttle control linkage should fail while the throttle valve is in either a partly or fully opened position.

' Herman THROTTLE RETURN SPRING REDUNDANCY SYSTEM Inventor:

Assignee:

Filed:

Appl. No.:

Ronald E. Herman, Warren, Mich.

Colt Industries Operating Corp.,

New York, NY.

Feb. 24, 1972 U.S. Cl. 123/198 DB, 123/198 R Int. Cl. F02b 77/00 Field of Search... 123/198 D, 198 DE, 198 DC,

References Cited UNITED STATES PATENTS Aug. 20, 1.974

Primary Examiner-Charles J. Myhre Assistant Examiner-R. H. Lazarus [5 7] ABSTRACT A throttle valve, situated within the induction passage bore of a fuel or air induction device, is carried by a throttle shaft for fixed rotation therewith; a lever arrangement fixedly connected to the-throttle shaft is operatively connected to a remotely situated operators foot-operated throttle control; a first throttle return spring is operatively connected to the first lever for returning the throttle valve to an idle position whenever the foot-operated throttle control is released; and a second safety spring'is provided for, in one embodiment of the invention, assuring the movement of the throttle valve to the idle position and, in another embodiment of the invention, de-actuating the engine ignition system, in the event that, for example, either the first throttle return spring or the associated throttle control linkage should fail while the throttle valve is in either a partly or fully opened posi- 1 tion.

14 Claims, 6 Drawing Figures PATENIEDwczmsn 3.830.213 sum aor 4 BACKGROUND OF THE INVENTION Heretofore, carburetors or other engine induction devices, employing an induction passage with a throttle valve therein, had a lever fixed to the throttle shaft which lever, in turn, was operatively connected to associated throttle control linkage (as the vehicle operators foot-controlled throttle pedal within the vehicle passenger compartment) and to a return spring for returning the throttle valve to an engine idle position when control over the throttle had been relinquished by the vehicle operator.

Even though such carburetors and induction devices have performed well in the past and have not shown any tendancy to experience failure of such a throttle return spring or the associated throttle control linkage, the United States Federal Government has, nevertheless, recently issued new proposed safety standards in regard to driver-operated throttle or accelerator control system.

Such standards, among other things, require that: (l) in the event the normal or usual throttle return spring should fail, means must be provided for assuring that the throttle will return to its idle position; and (2) in the event the associated throttle control linkage should fail, means must be provided for assuring that the throttle will return to its idle position.

Accordingly, the invention as herein disclosed is primarily concerned with the solution of the above as well as other related problems.

SUMMARY OF THE INVENTION According to the invention, an automatic throttle return device comprises first lever means operatively connected to an associated throttle shaft and throttle valve for rotation therewith, first spring means effective for rotating said first lever means and throttle valve to an idle position during normal operating conditions, and second safety spring means effective upon failure of said first spring means for assuring rotation of said throttle valve to said idle position, without appreciably increasing throttle opening effort.

Various general and specific objects and advantages of the invention will become apparent when reference is made to the following detailed description considered in conjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS In the drawings, wherein for purposes of clarity certain details and elements may be omitted from one or more views:

FIG. 1 is basically a side elevational view of a carburetor, or other induction device, embodying the teachings of the invention, along with associated linkage and control means;

FIG. 2 is an enlarged perspective view of a fragmentary portion of one of the levers employed and shown in the embodiment of FIG. 1;

FIG. 3 is a view similar to FIG. 1 but illustrating the FIG. 5 is a view similar to FIG. 1 but illustrating a second embodiment of the invention; and

FIG. 6 is a view similar to FIG. 5 but illustrating a third embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in greater detail to the drawings, FIG. 1 fragmentarily illustrates a portion of an induction device, such as a carburetor 10, mounted atop an intake manifold 12 of a related internal combustion engine. An induction passage 14 formed through body 16 of induction device 10 communicates at its upper end with a source of air at its lower end with the interior 18 of intake manifold 12. A generally transversely extending rotatable throttle shaft 20 has a throttle valve 22, situated within the induction passage 14, secured thereto for rotation therewith.

A first lever 24, having arm portions 26 and 28, is suitably fixedly secured to throttle shaft 20 for rotation therewith. As shown, arm portions 26 and 28 may be disposed on opposite sides of shaft 20 with arm portion 28 being operatively connected, as at 30, to one end of a safety return spring 32 which has its other end 34 fixedly anchored as at 36. Arm portion 26 of lever 24 is pivotally connected to a second lever 38 as by suitable interconnecting pivot means 40.

The upper end of lever 38 is operatively connected as at 42 to one end of a throttle return spring 44 which has its other end 46 secured to suitable anchor means 48. Generally between pivot 40 and the connection of spring 44, lever 38 is pivotally connected, as at 49, to one end 50 of a motion transmittting linkage or rod member 52 comprising a portion of the associated.

throttle control means 54.

As somewhat schematically illustrated, the throttle control means 54 may be further comprised of a lever 56 pivotally secured asat 58 to a suitable support 60 and having its upper arm 62 pivotally connected as at 64 to end 66 of linkage or rod 52. The lower arm 68 has an end 70 abutingly engaged by as by a vehicle operators foot controlled throttle pedal 72 rotatable about a pivot support 74.

FIG. 2, an enlarged perspective view of a fragmentary portion of the lever 38 of FIG. 1 further illustrates lever 38 as including a generally laterally extending arm-like abutment portion 76. Abutment 76 is of a size and configuration so as to have the generally upper surface 78 thereof abut against the generally lower edge surface 80 of lever 24 when levers 38 and 24 are, for example, in the position illustrated in FIG. 1.

OPERATION OF THE INVENTION For purposes of description, let it be first assumed that the elements are in the respective positions as shown in FIG. 1. At this time the throttle valve 22 will be in the nominally closed or idle position within induction passage 14 as generally depicted.

During normal operation when opening movement of the throttle valve 22 is desired, foot-operated throttle pedal 72 is rotated counter-clockwise about its pivot support 74 causing lever 56 to rotate clockwise and linkage 52, connected thereto, to move generally to the right.

Such movement of rod 52, in turn, causes clockwise rotation of levers 38 and 24 along with throttle shaft 20 and throttle valve 22. Such rotation is accomplished locking abutment surface 78 against the lower edge 80 of lever 24 so as to functionally form a single or solid lever means. Consequently, as rod 52 continues its movement to the right the lever means comprised of levers 38 and 24 are progressively rotated clockwise about the axis of shaft thereby further rotating and opening throttle valve 22. When foot-controlled pedal 72 reaches a maximum position illustrated at 72a, lever 56 correspondingly attains a position illustrated at 560 with motion transmitting linkage 52 assuming a position fragmentarily illustrated at 52a of FIG. 1, causing the throttle valve 22 to be rotated to a fully or wide open position as shown in FIG. 3. At this time the throttle return spring 44 and safety return spring 32 will have been stretched as shown. It should be mentioned that, even though not at all necessary to the successful practice of the invention, resilient means 82, of relatively low resilient force, may be provided as generally depicted in FIG. 1 as to continually provide at least some small biasing force thereby maintaining under all normal operating conditions, including curb idle, a minimal moment couple on lever 38 about connection 42.

Referring to FIG. 3, as the force on the throttle pedal 72 is released (as when the throttle valve 22 is in any of its partly opened positions) throttle return spring 44 rotates inter-locked levers 38 and 24 counterclockwise about the axis of throttle shaft 20 thereby correspondingly rotating throttle valve 22 back toward its curb idle position shown in FIG. 1. During this time, of course, safety spring 32 also continually contributes a force tending to move the throttle valve 22, directly through lever 24, toward its nominally closed or curb idle position.

Now, referring to FIGS. 3 and 4, let it be assumed that the throttle valve 22 has been rotated to some partly opened (part throttle) position or even to a wide open position as shown in FIG. 3 and that at such time the throttle return spring 44 fractured or in some other way functionally failed.

If spring 44 did break and become detached as generally depicted in FIG. 4, the force moment couple on lever 38 previously referred to and established by the cooperative action of spring 44 and linkage 52 would immediately cease to exist. Consequently, this would permit safety spring 32 to rotate lever 24 counterclockwise about the axis of throttle shaft 20 thereby moving throttle valve 22 to its nominally closed or curb idle position as shown in FIG. 4 (also in FIG. 1). As can be seen, the linkage 52 can in no way prevent such rotation of lever 24 by spring 32 because of the pivot connection 40 therebetween which enables lever 38 to be rotated generally clockwise thereabout assuming a position generally depicted at 38b with linkage 52 assuming a corresponding position 52b.

The same results would, of course, be obtained even if both spring 44 and linkage means 54 simultaneously failed. That is, the force moment couple would again cease to exist and throttle safety spring 32 would again return throttle 22 to its nominally closed position.

As depicted in FIGS. 1 and 4, in one version of the invention, when spring 44 should fail and the throttle valve 22 is returned to its curb idle position, the effective lengths and geometry of lever 38, linkage 52, lever 56 and pedal 72 may be such as to place pedal 72 in a position (as at 72a) wherein no further movement of pedal 72 is possible or sufficient to cause any subsequent opening movement of throttle valve 22. However, it is contemplated that the said effective lengths and geometry may be such as to enable a slight degree of opening movement of throttle valve 22 to occur upon further depression of the pedal 72. This would be beneficial in instances where one wanted to avoid the possible problem of having the safety return spring return and maintain the throttle valve 22 to its curb idle position in, for example, a condition of heavy vehicular traffic. This slight degree of opening movement would enable the vehicle operator to at least slowly drive his vehicle off the lanes of traffic and into a safe parking area.

It should be apparent that the invention is not limited to the use of a spring as specifically shown at 32. For example, and not by way of limitation, safety springs could take the form of torsion spring connected to lever 24 or even torsion springs interconnecting levers 38 and 24. Other arrangements and resilient devices (not necessarily limited to mechanical springs) will, of course, be apparent to those skilled in the art.

SECOND EMBODIMENT OF THE INVENTION FIG. 5 illustrates a second embodiment of the invention. A carburetor 84, situated atop an intake manifold 86 of a related internal combustion engine, has an induction passage 88 formed through the body 90 thereof so as to communicate at its upper end with a source of air and at its lower end with the interior 92 of the intake manifold 86. A generally transversely extending rotatable throttle shaft 94 has a throttle valve 96, situated within the induction passage 88, secured thereto for rotation therewith.

A throttle actuating lever 98, fixedly secured to throttle shaft 94 for rotation therewith, has its upper arm pivotally connected as at 102 to one end 104 of motion transmitting linkage or rod 106. Rod 106 may be considered as comprising a portion of related throttle control means 108 which is further comprised of a lever 110 pivotally connected as at 112 to related support means 114. As shown, rod 106 may have its other end 116 pivotally connected to the upper arm 118 of lever 110 which has its lower arm 120 pivotally connected to additional linkage means 122 pivotally connected to, for example, the vehicle operators footcontrolled throttle pedal 124 which is pivotally connected for roation about a pivot support 126.

A pressure responsive diaphragm assembly 128 is illustrated as being comprised of a pressure responsive diaphragm 130 (or any other suitable member) having its peripheral edge secured between housing-like members 132 and 134. Housing section 132 is provided with a clearance aperture 136 pennitting the free passage therethrough of a connecting linkage 138 as well as the free passage of atmospheric pressure into the chamber 140 generally between housing 132 and diaphram 130. Suitable retainer plates 142 and 144 disposed at opposite sides of diaphragm 130 serve to connect one end of rod or linkage means 138 to the diaphragm 130 for movement therewith. The other end 146 of rod 138 is pivotally connected as at 148 to the lower arm 150 of lever 98. The diaphragm assembly 128 may be secured to a suitable fixed support 152.

A throttle return spring 154 has one end 156 connected to lever arm 100 as at 158 while its other end 160 is connected as at 162 to end 164 of a moveable valving member 166 having a generally cylindrical shank portion 168 and an enlarged head portion 170.

Valving member 166 comprises a portion of a valve assembly 172 which further comprises a housing or body 174 having a cylindrical passageway 176 formed therein for the close reception therethrough of said shank 168. An enlarged chamber 178 accommodates a compression spring 180 (of a resilient force less than that of throttle return spring 154) engaging the head portion 170 and continually urging the valve member 166 to the left to a position generally depicted in phantom line at 170a. Even though the head portion 170 is freely received within a second enlarged chamber 182, the periphery thereof may, if desired, be relieved as by flatted or otherwise relieved portions or grooves 184. The enlarged chamber 182 provides an annular shoulder 186 against which the head portion 170 may abut so as to limit the travel of the valving member 166 to the right.

Chamber 178 is placed in communication with a suitable source of vacuum as, for example, manifold vacuum existing within the interior 92 of intake manifold 86 as by means of conduit portion 188 and conduit means 190 including fitting means 198 communicating with the said interior 92. A second conduit portion 194 formed in housing 174 communicates with chamber 196, formed generally between diaphram 130 and housing section 134, as by suitable conduit means 198.

Shank 168 of valving member 166 has a portion 200 of reduced diameter defined at its opposite ends by radial annular surfaces 202 and 204 which, as will become apparent, serve as valving surfaces to selectively complete and terminate communication between chambers 178 and 198.

A third conduit 206 formed in housing 174 is in communication with-the space between end valving surfaces 202 and 204 whenever valving member 166 is in the position shown.

OPERATION OF SECOND EMBODIMENT OF THE INVENTION For purposes of description, let it be first assumed that the elements are in the respective positions as shown in solid line in FIG. 5. At this time the throttle valve 96 will be in the nominally closed or curb idle position within the induction passage as generally depicted.

During normal operation when opening movement of the throttle valve 96 is desired, foot-operated throttle pedal 124 is rotated counter-clockwise about its pivot support 126 causing lever 110 to rotate clockwise and linkage 106, connected thereto, to move generally to the right. Such movement of linkage 106 in turn causes throttle lever 98 to rotate clockwise about the axis of throttle shaft 94 thereby correspondingly rotating shaft 94 and throttle valve 96 carried thereby in the throttleopening direction. During this time spring 154 is stretched and continually resiliently resists the clockwise rotation of lever 98 and the opening movement of throttle valve 96. The tension spring 154, during all normal conditions of engine operation as well as during engine shutdown, is sufficient to overcome the force of spring 180 and thereby maintain valve member 166 in a position as shown within head portion 170 against the stop surface 186. With valving member 166 maintained in such a position, atmospheric pressure is directed to diaphragm assumbly chamber 196 via conduit means 198, conduit portion 194, the space between valving surfaces 202, 204 and conduit portion 206.

Therefore, no pressure differential is experienced across diaphragm member and diaphragm member is thereby freely moved as from the position shown in solid line to the position shown in phantom line at 130a (which would correspond to a wide open throttle position) via linkage means 138 connected to arm of lever 98. Continued rotation of pedal 124 eventually results in throttle valve 96 attaining a wide open position at which time lever 98 would assume a position depicted in phantom line at 9811' and lever 110 would assume a position generally depicted in phantom line at 110a.

If the throttle valve 96 is in any partly opened or fully opened position and the opening force on the throttle pedal 124 is removed, throttle return spring 154 rotates throttle lever 98 counter-clockwise along with shaft 94, secured thereto, and throttle valve 96 toward the nominally closed or curb idle throttle position illustrated.

However, for purposes of discussion, let it be assumed that foot-operated pedal 124 and lever 98 have been rotated to a fully opened throttle position, or to some intermediate partly opened throttle position, and at that time spring 154 fractures or fails in some other way.

As a consequence of such failure of spring 154, spring 180 would move valving member 166 to the left until head portion assumes a position as generally depicted in phantom line at 170a. Accordingly, valving surface 204 is moved to a position depicted at 204a while the opposite valving surface 202 moves to a position depicted at 202a. As a result of such movement of valving member 166, communicating with the atmosphere through conduit 206 is terminated while communication between chamber 178 and conduit 194 is completed. Consequently, the vacuum generated within interior 92 of intake manifold 86 is communicated via conduit means 198 to chamber 196 of diaphragm assembly 128.

If it is assumed that at the instant the valving member 166 moved to the left, diaphragm member 130 was in a position shown at 130a, then as soon as the vacuum was communicated to chamber 196 a pressure differential would be created across diaphragm 130a causing it to move to its solid-line position at 130. In so moving to the right diaphragm 130 causes lever 98 along with throttle valve 96 to rotate counter-clockwise until the throttle valve returns to its nominally closed or curbidle position.

THIRD EMBODIMENT OF THE INVENTION FIG. 6, wherein elements like or similar to those of FIG. 5 are identified with like reference numbers, illustrates a third embodiment of the invention as comprising a switch assembly, shown in somewhat simplified manner at 210, employed for shutting-off the engine upon loss of the throttle retumspring 154 or its function.

The switch assembly 210 may be comprised of a relatively fixed support portion 212 slideably holding therein a moveable switch portion 214 carrying a contact 216 moveable therewith and, during normal conditions of engine operation, engaging and bridging fixed electrical contacts 218 and 220. A head portion 222 serves to engage one end of a compression spring 224 which is seated, at its other end, against the fixed support 212. The opposite end of switch member 214 may be connected as at 226 to end 160 of throttle return spring 154 which, in all conditions of normal operation, is sufficient to overcome the force of spring 224.

An ignition distributor assembly, well known in the art and somewhat schematically disclosed at 246, is comprised of terminals 248, 250, 252 and 254 which are sequentially electrically contact with the distributor rotor 256, which, in turn, is electrically connected via conductor means 258 to secondary winding 242. Terminals 248, 250, 252, and 254 are, in turn, respectively electrically connected via conductor means 260, 262, 264 and 266 to the engine spark plug or igniter assemblies 268, 270, 272 and 274 which are grounded as at 276. As rotor 256 is rotated in timed relationship to the engine, rotor is sequentially brought into juxtaposition with the terminals 250, 252, 254 and 248 at which time, a pulse generated in the secondary winding 242, an electrical spark is created across the terminals of the respective related spark plug assembly.

A set of breaker contacts 278 and 280, one of which is often fixed while the other is moveable, is connected to the primary winding 238 via conductor means 282 and is grounded as at 284. As is customary in the prior art, suitable capacitance means 286 may be provided in parallel relationship to contacts 278 and 280 in order to prevent arcing therebetween whenever contacts 278 and 280 are opened.

As is well known in the art, the opening and closing of contacts 287 and 280 is accomplished in timed relationship to the.engine speed and rotation of rotor 256. Whenever contacts 278 and 280 open, the field about secondary winding 242 collapses thereby generating the voltage pulse necessary to create the spark in the related spark plug.

OPERATION OF THE THIRD EMBODIMENT OF THE INVENTION With the igniton switch 230 closed the operation of the foot-operated pedal 124 lever 98 and throttle valve 96, during all normal conditions of operations is as that described with reference to FIG. and therefore will not be repeated here.

Let it now be assumed that foot-operated pedal 124 lever 110 and lever 98 have been rotated to either a fully opened throttle position or to some intermediate partly opened throttle position and that at such time spring 154 either fractured or in some way become inoperative. If this were to happen, spring 224 in switch assembly 210 would move switch member 214 to the left thereby causing moveable contact 216 to move away from fixed contacts 218 and 220 thereby opening the circuit leading to the primary winding 238 of ignition coil assembly 240 and de-activating the vehicular ignition system causing a shut-down of the associated engine.

It should be apparent that the switching means 210 could be employed to in other ways either cause engine shut-down or reduce the engine speed. That is, since the making and breaking of the circuit through fixed contacts 218 and 220 is primarily employed as an indicia of the condition of the return spring 154, such indicia could be employed, for example, for providing an electrically actuated engine speed governor system or even reducing the fuel flow to the engine by other electrically actuated fluid flow control means.

Even though only three preferred embodiments of the invention have been disclosed and described, it is apparent that other embodiments and modifications of the invention are possible within the scope of the appended claims.

I claim:

1. Apparatus for assuring the return from a partly opened or fully opened position of a throttle valve to a more closed position, comprising a control for said throttle valve, first means operatively connected to an associated throttle shaft carrying said throttle valve for rotation therewith, operating means between said control and said first means, spring means effective for rotating said first means and throttle valve to an idle position during normal operating conditions, and second throttle return means operatively connected to said throttle valve, said second throttle return means being constructed and arranged so as to be effective upon failure of said spring means to assure automatic rotation of said throttle valve toward said more closed position even though said operating means is operative and in a more open throttle position.

2. Apparatus according to claim 1, wherein said second throttle return means comprises second throttle return spring means.

3. Apparatus according to claim 1, wherein said second throttle return means comprises pressure responsive motor means.

4. Apparatus according to claim 3, wherein said first spring means is operatively connected to associated valving means, said valving means being effective during all times that said first spring means is functionally operative for preventing communication between a source of vacuum and one side of a pressure responsive member comprising said pressure responsive motor means, said valving means being effective whenever said first spring becomes functionally ineffective to complete said communication between said source of vacuum and said one side of said pressure responsive member thereby causing said throttle valve to be rotated toward said idle position.

5. Apparatus according to claim 4, wherein said valv ing means comprises a movable valve member operatively connected to said first spring means, second spring means continually resiliently urging said moveable valve member in a direction opposite to the direction urged by said first spring means, and wherein said course of vacuum comprises engine intake manifold vacuum generated within the intake manifold of an associated internal combustion engine.

6. Apparatus according to claim 4, wherein said pressure responsive motor means comprises a pressure responsive diaphragm motor assembly, and wherein said pressure responsive member comprises a pressure responsive diaphragm member.

7. Apparatus according to claim 1, wherein said first means comprises a first rotatable lever member connected to said throttle shaft for rotation therewith, a second lever member pivotally connected to said first lever member, wherein said first spring means isoperatively connected to said second lever member fbr normally urging said first and second lever members and said throttle valve in a first direction toward said idle position, abutment means carried by at least one of said lever members for causing abuting engagement between said first and second lever members and thereby limiting the degree of pivotal rotation of said second lever member with respect to said first lever member when urged in said first direction by said first spring means, wherein said second throttle return means comprises second spring means continually urging said first and second lever members in directions relative to each other as to tend to have said first and second lever members move in directions away from said abuting engagement, and further comprising throttle control linkage means operatively connected to said second lever member.

8. Apparatus according to claim 7, wherein said second spring means is operatively connected to said first lever member.

9. Apparatus according to claim 7, wherein said throttle control linkage means is operatively connected to .said second lever member generally between the connection of said second lever member to said first spring means and the pivotal connection of said second lever member to said first spring means and the pivotal connection of said second lever member to said first lever member.

10. Apparatus according to claim 7, wherein said abutment means comprises an abutment portion effective for achieving said abuting engagement at a point generally between the pivotal connection of said second lever member to said first lever member and the axis of rotation of said first lever member.

11. In combination with an internal combustion enfirst means for causing at least a reduction in the speed of said engine, said second means being constructed and arranged so that at least a limited subsequent increase in engine speed,'exceeding said reduced speed, is obtainable through said failed associated throttle control mechanism by actuation thereof, in the usual throttle opening mode of operation;

12. The combination of claim 11, wherein said first means comprises electrical switching means, and wherein said second means comprises electrical circuitry defining an ignition system of said internal combustion engine, and wherein said switching means is effective for opening and closing said electrical circuitry in accordance with actuation of said switching means.

13. The combination of claim 12, wherein said switching means is resiliently biased toward a closed circuit position by first resilitent throttle return means comprising said associated throttle control mechanism.

14. The combination of claim 13, wherein said electrical circuitry comprises an ignition coil having primary and secondary windings, and wherein said switching means is placed in circuit generally between said primary winding and a source of electrical potential. 

1. Apparatus for assuring the return from a partly opened or fully opened position of a throttle valve to a more closed position, comprising a control for said throttle valve, first means operatively connected to an associated throttle shaft carrying said throttle valve for rotation therewith, operating means between said control and said first means, spring means effective for rotating said first means and throttle valve to an idle position during normal operating conditions, and second throttle return means operatively connected to said throttle valve, said second throttle return means being constructed and arranged so as to be effective upon failure of said spring means to assure automatic rotation of said throttle valve toward said more closed position even though said operating means is operative and in a more open throttle position.
 2. Apparatus according to claim 1, wherein said second throttle return means comprises second throttle return spring means.
 3. Apparatus according to claim 1, wherein said second throttle return means comprises pressure responsive motor means.
 4. Apparatus according to claim 3, wherein said first spring means is operatively connected to associated valving means, said valving means being effective during all times that said first spring means is functionally operative for preventing communication between a source of vacuum and one side of a pressure responsive member comprising said pressure responsive motor means, said valving means being effective whenever said first spring becomes functionally ineffective to complete said communication between said source of vacuum and said one side of said pressure responsive member thereby causing said throttle valve to be rotated toward said idle position.
 5. Apparatus according to claim 4, wherein said valving means comprises a movable valve member operatively connected to said first spring means, second spring means continually resiliently urging said moveable valve member in a direction opposite to the direction urged by said first spring means, and wherein said course of vacuum comprises engine intake manifold vacuum generated within the intake manifold of an associated internal combustion engine.
 6. Apparatus according to claim 4, wherein said pressure responsive motor means comprises a pressure responsive diaphragm motor assembly, and wherein said pressure responsive member comprises a pressure responsive diaphragm member.
 7. Apparatus according to claim 1, wherein said first means comprises a first rotatable lever member connected to said throttle shaft for rotation therewith, a second lever member pivotally connected to said first lever member, wherein said first spring means is operatively connected to said second Lever member for normally urging said first and second lever members and said throttle valve in a first direction toward said idle position, abutment means carried by at least one of said lever members for causing abuting engagement between said first and second lever members and thereby limiting the degree of pivotal rotation of said second lever member with respect to said first lever member when urged in said first direction by said first spring means, wherein said second throttle return means comprises second spring means continually urging said first and second lever members in directions relative to each other as to tend to have said first and second lever members move in directions away from said abuting engagement, and further comprising throttle control linkage means operatively connected to said second lever member.
 8. Apparatus according to claim 7, wherein said second spring means is operatively connected to said first lever member.
 9. Apparatus according to claim 7, wherein said throttle control linkage means is operatively connected to said second lever member generally between the connection of said second lever member to said first spring means and the pivotal connection of said second lever member to said first spring means and the pivotal connection of said second lever member to said first lever member.
 10. Apparatus according to claim 7, wherein said abutment means comprises an abutment portion effective for achieving said abuting engagement at a point generally between the pivotal connection of said second lever member to said first lever member and the axis of rotation of said first lever member.
 11. In combination with an internal combustion engine having a motive fluid induction device with a variably positionable throttle valve for controlling the rate of motive fluid through said induction device to said engine, apparatus for assuring at least a reduction in engine speed in the event of failure of associated throttle control mechanism when said throttle valve is in either a partly or fully opened position, said apparatus comprising first means actuated in response to indicia of said failure of said associated throttle control mechanism, and second means responsive to acutation of said first means for causing at least a reduction in the speed of said engine, said second means being constructed and arranged so that at least a limited subsequent increase in engine speed, exceeding said reduced speed, is obtainable through said failed associated throttle control mechanism by actuation thereof, in the usual throttle opening mode of operation.
 12. The combination of claim 11, wherein said first means comprises electrical switching means, and wherein said second means comprises electrical circuitry defining an ignition system of said internal combustion engine, and wherein said switching means is effective for opening and closing said electrical circuitry in accordance with actuation of said switching means.
 13. The combination of claim 12, wherein said switching means is resiliently biased toward a closed circuit position by first resilitent throttle return means comprising said associated throttle control mechanism.
 14. The combination of claim 13, wherein said electrical circuitry comprises an ignition coil having primary and secondary windings, and wherein said switching means is placed in circuit generally between said primary winding and a source of electrical potential. 